Curable composition

ABSTRACT

Provided are a curable composition and its use. The curable composition can exhibit excellent processability and workability. The curable composition exhibits excellent light extraction efficiency, hardness, thermal and shock resistance, moisture resistance, gas permeability and adhesiveness, after curing. In addition, the curable composition can provide a cured product that exhibits long-lasting durability and reliability even under harsh conditions, and that does not cause whitening and surface stickiness.

FIELD

The present application relates to a curable composition and its use.

BACKGROUND

A light-emitting diode (LED), for example, particularly a blue orultraviolet (UV) LED having an emission wavelength of approximately 250nm to 550 nm, is a high-brightness product using a GaN-based compoundsemiconductor such as GaN, GaAlN, InGaN or InAlGaN. In addition, it ispossible to form a high-quality full-color image by a method ofcombining red and green LEDs with a blue LED. For example, a techniqueof manufacturing a white LED by combining a blue or UV LED with afluorescent material is known.

Such LEDs are widely used as backlights for liquid crystal displays(LCDs) or as lighting.

As an LED encapsulant, an epoxy resin having high adhesive strength andexcellent mechanical durability is widely used. However, the epoxy resinhas lower light transmittance in a blue light or UV ray region, and lowheat and light resistance. For example, Japanese Patent Application Nos.H11-274571, 2001-196151 and 2002-226551 present techniques for solvingthe above-described problems. However, encapsulants disclosed in theabove references do not have sufficient heat resistance and lightresistance.

Technical Description

The present application provides a curable composition and its use.

Solution

One aspect of the present application provides a curable compositionincluding components that can be cured by hydrosilylation, for example,a reaction between an aliphatic unsaturated bond and a hydrogen atom.For example, the curable composition may include a polymerizationproduct including a polyorganosiloxane having a functional groupincluding an aliphatic unsaturated bond (hereinafter, referred to as“polyorganosiloxane (A)”).

The term “M unit” used herein may refer to a monofunctional siloxaneunit possibly represented as (R₃SiO_(1/2)) in the art, and the term “Dunit” used herein may refer to a bifunctional siloxane unit possiblyrepresented as (R₂SiO_(2/2)) in the art, the term “T unit” used hereinmay refer to a trifunctional siloxane unit possibly represented as(RSiO_(3/2)) in the art, and the term “Q unit” used herein may refer toa tetrafunctional siloxane unit possibly represented as (SiO_(4/2)).Here, R is a functional group binding to a silicon (Si) atom, and maybe, for example, a hydrogen atom, a hydroxyl group, an epoxy group, analkoxy group, or a monovalent hydrocarbon group.

The polyorganosiloxane (A) may have, for example, a linear orpartially-crosslinked structure. The term “linear structure” may referto a structure of a polyorganosiloxane composed of the M and D units. Inaddition, the term “partially-crosslinked structure” may refer to asufficiently long linear structure of a polyorganosiloxane, which isderived from the D unit, and to which the T or Q unit, for example, theT unit is partially introduced. In one embodiment, thepolyorganosiloxane having a partially-crosslinked structure may refer toa polyorganosiloxane having a ratio (D/(D+T+Q)) of the D unit withrespect to all D, T and Q units included in the polyorganosiloxane of0.65 or more.

In one embodiment, the polyorganosiloxane (A) having apartially-crosslinked structure may include D and T units sharing oneoxygen atom and linked to each other. The linked units may berepresented by, for example, Formula 1.

In Formula 1, R^(a) and R^(b) are each independently an alkyl group, analkenyl group, or an aryl group, and R^(c) is an alkyl group or an arylgroup.

In Formula 1, R^(c) and R^(b) may be, for example, both simultaneouslyan alkyl group or an aryl group.

The polyorganosiloxane (A) having a partially-crosslinked structure mayinclude at least one unit of Formula 1. The unit of Formula 1 is of atype in which a silicon atom of the D unit and a silicon atom of the Tunit are directly bound by means of an oxygen atom among the siloxaneunits forming the polyorganosiloxane (A). For example, as will bedescribed later, the polyorganosiloxane including the unit of Formula 1may be prepared by polymerizing, for example, ring-opening polymerizinga mixture including a cyclic siloxane compound. When the method isapplied, a polyorganosiloxane including the unit of Formula 1 and havingminimum amounts of silicon atoms binding to an alkoxy group and siliconatoms binding to a hydroxyl group in its structure may be prepared.

The polyorganosiloxane (A) may include at least one functional groupincluding an aliphatic unsaturated bond, for example, at least onealkenyl group. For example, a ratio (Ak/Si) of moles of the functionalgroup including an aliphatic unsaturated bond (Ak) with respect to molesof all silicon atoms (Si) in the polyorganosiloxane (A) may beapproximately 0.01 to 0.3, or 0.02 to 0.25. As the molar ratio (Ak/Si)is controlled to 0.01 or more, or 0.02 or more, reactivity can besuitably maintained, and leakage of an unreacted component from asurface of a cured product can be prevented. In addition, as the molarratio (Ak/Si) is controlled to 0.3 or less, or 0.25 or less, crackresistance of the cured product can be excellently maintained.

The polyorganosiloxane (A) may include an aryl group, for example, atleast one aryl group binding to a silicon atom. For example, apercentage (100×Ar/R) of moles of the aryl group (Ar) with respect tomoles of all silicon-binding functional groups (R) included in thepolyorganosiloxane (A) may be approximately 30% to 60%. Within such arange, the composition can have excellent processability and workabilitybefore curing, and can excellently maintain moisture resistance, lighttransmittance, refractive index, light extraction efficiency andhardness after curing. Particularly, as the percentage (100×Ar/R) ismaintained at 30% or more, mechanical strength and gas permeability ofthe cured product can be suitably ensured, and as the percentage ismaintained at 60% or less, the crack resistance and light transmittanceof the cured product can be excellently maintained.

The polyorganosiloxane (A) may include a unit of Formula 2 and a unit ofFormula 3 as D units.(R¹R²SiO_(2/2))  [Formula 2](R³ ₂SiO_(2/2))  [Formula 3]

In Formulas 2 and 3, R¹ and R² are each independently an epoxy group ora monovalent hydrocarbon group, and R³ is an aryl group. In oneembodiment, the R¹ and R² are each independently an alkyl group.

The term “monovalent hydrocarbon group” used herein, unless particularlydefined otherwise, may refer to a monovalent residue derived from acompound composed of carbon and hydrogen or a derivative thereof. Forexample, the monovalent hydrocarbon group may include 1 carbon atoms to25 carbon atoms. The monovalent hydrocarbon group may be an alkyl group,an alkenyl group, an alkynyl group, or an aryl group.

The term “alkyl group” used herein may refer to, unless particularlydefined otherwise, an alkyl group having 1 to 20, 1 to 16, 1 to 12, 1 to8, or 1 to 4 carbon atoms. The alkyl group may have a linear, branchedor cyclic structure. In addition, the alkyl group may be optionallysubstituted with at least one substituent.

The term “alkenyl group” used herein may refer to, unless particularlydefined otherwise, an alkenyl group having 2 to 20 carbon atoms, 2 to 16carbon atoms, 2 to 12 carbon atoms, 2 to 8 carbon atoms, or 2 to 4carbon atoms. The alkenyl group may have a linear, branched or cyclicstructure, and may be optionally substituted with at least onesubstituent.

The term “alkynyl group” used herein may refer to, unless particularlydefined otherwise, an alkynyl group having 2 to 20 carbon atoms, 2 to 16carbon atoms, 2 to 12 carbon atoms, 2 to 8 carbon atoms, or 2 to 4carbon atoms. The alkynyl group may have a linear, branched or cyclicstructure, and may be optionally substituted with at least onesubstituent.

The term “aryl group” used herein may refer to, unless particularlydefined otherwise, a monovalent residue derived from a compoundincluding a benzene ring or a structure in which at least two benzenerings are condensed or connected by a covalent bond with one or twocarbon atoms or a derivative thereof. In the range of the aryl group, afunctional group conventionally referred to as an aralkyl group orarylalkyl group may be included, in addition to a functional groupconventionally referred to as an aryl group. The aryl group may be, forexample, an aryl group having 6 to 25 carbon atoms, 6 to 21 carbonatoms, 6 to 18 carbon atoms, or 6 to 12 carbon atoms. The aryl group maybe a phenyl group, a dichlorophenyl group, a chlorophenyl group, aphenylethyl group, a phenylpropyl group, a benzyl group, a tolyl group,a xylyl group, or a naphthyl group.

The term “epoxy group” used herein may refer to, unless particularlydefined otherwise, a monovalent residue derived from a cyclic etherhaving three ring-forming atoms or a compound including the cyclicether. The epoxy group may be a glycidyl group, an epoxyalkyl group, aglycidoxyalkyl group or an alicyclic epoxy group. An alicylic epoxygroup may include a monovalent residue derived from a compound includingan aliphatic hydrocarbon ring structure, and a structure of an epoxygroup formed by two carbon atoms of the aliphatic hydrocarbon ring. Thealicyclic epoxy group may be an alicyclic epoxy group having 6 to 12carbon atoms, for example, a 3,4-epoxycyclohexylethyl group.

As a substituent that may be optionally substituted to an epoxy group,or a monovalent hydrocarbon group, a halogen such as chlorine orfluorine, a glycidyl group, an epoxyalkyl group, a glycidoxyalkyl group,an epoxy group such as an alicyclic epoxy group, an acryloyl group, amethacryloyl group, an isocyanate group, a thiol group, or a monovalenthydrocarbon group may be used, but the present application is notlimited thereto.

In the polyorganosiloxane (A), a ratio (Dm/Dp) of moles (Dm) of thesiloxane unit of Formula 2 with respect to moles (Dp) of the siloxaneunit of Formula 3 may be, for example, in the range of approximately 0.3to 2.0, 0.3 to 2.0, 0.3 to 1.5, or 0.5 to 1.5. Within such a range ofthe ratio, a curable composition having excellent mechanical strength,no surface stickiness, long-lasting high light transmittance bycontrolling moisture and gas permeability, and long-lasting durabilitycan be provided.

A percentage (100×Dp/D) of moles (Dp) of the siloxane unit of Formula 3with respect to moles (D) of all D units included in thepolyorganosiloxane (A) may be approximately 30% or more, 30% to 65%, or30% to 60%. Within such a range of the percentage, mechanical strengthis excellent, there is no surface stickiness, and moisture and gaspermeability can be controlled to ensure long-lasting durability.

A percentage (100×Dp/ArD) of moles (Dp) of the siloxane unit of Formula3 with respect to moles (ArD) of a D unit including an aryl group amongall D units included in the polyorganosiloxane (A) may be 70% or 80% ormore. The upper limit of the percentage (100×Dp/ArD) is not particularlylimited, and may be, for example, 100%. Within such a range of thepercentage, the composition can exhibit excellent processability andworkability before curing, and excellently maintain mechanical strength,gas permeability, moisture resistance, light transmittance, refractiveindex, light extraction efficiency, and hardness after curing.

In one embodiment, the polyorganosiloxane (A) may have an averageempirical formula of Formula 4.(R⁴ ₃SiO_(1/2))_(a)(R⁴₂SiO_(2/2))_(b)(R⁴SiO_(3/2))_(c)(SiO_(4/2))_(d)  [Formula 4]

In Formula 4, R⁴ are each independently an epoxy group or a monovalenthydrocarbon group, at least one of R⁴ is an alkenyl group, and at leastone of R⁴ is an aryl group. The alkenyl and aryl groups may be included,for example, to satisfy the above-described molar ratio.

The expression “polyorganosiloxane is represented as a certain averageempirical formula” used herein means that the polyorganosiloxane is asingle component represented as a certain average empirical formula, ora mixture of at least two components, and an average of compositions ofcomponents in the mixture is represented as the average empiricalformula.

In the average empirical formula of Formula 4, a, b, c and d are molarratios of respective siloxane units of the polyorganosiloxane (A), andfor example, a and b may each be a positive number, and c and d may eachbe 0 or a positive number. For example, when a sum (a+b+c+d) of themolar ratios is adjusted to be 1, a may be 0.01 to 0.3, b may be 0.65 to0.97, c may be 0 to 0.30 or 0.01 to 0.30, d may be 0 to 0.2, andb/(b+c+d) may be 0.7 to 1. When the polyorganosiloxane (A) has apartially-crosslinked structure, b/(b+c+d) may be approximately 0.65 to0.97 or 0.7 to 0.97. As ratios of the siloxane units are controlled asdescribed above, suitable physical properties according to anapplication can be ensured.

In another example, the polyorganosiloxane (A) may have an averageempirical formula of Formula 5.(R⁵R⁶ ₂SiO_(1/2))_(e)(R⁷R⁸SiO_(2/2))_(f)(R⁹₂SiO_(2/2))_(g)(R¹⁰SiO_(3/2))_(h)  [Formula 5]

In the average empirical formula of Formula 5, R⁵ to R¹⁰ may be eachindependently an epoxy group or a monovalent hydrocarbon group. Here, atleast one of R⁵ and R⁷ to R⁹ may be an alkenyl group, and at least oneof R⁵ and R⁷ to R⁹ may be an aryl group. For example, in the averageempirical formula, R⁷ and R⁸ may be each independently an alkyl group,and R⁹ may be an aryl group.

In the average empirical formula of Formula 5, e, f, g and h may bemolar ratios of respective siloxane units of the polyorganosiloxane (A),and for example, e may be a positive number, f and g may be eachindependently 0 or a positive number, and h may be 0 or a positivenumber. When a sum (e+f+g+h) of the ratios is adjusted to be 1, e may be0.01 to 0.3, f may be 0 to 0.97 or 0.65 to 0.97, g may be 0 to 0.97 or0.65 to 0.97, and h may be 0 to 0.30 or 0.01 to 0.30. Here,(f+g)/(f+g+h) may be 0.7 to 1.

When the polyorganosiloxane (A) has a partially-crosslinked structure,(f+g)/(f+g+h) may be 0.7 to 0.97 or 0.65 to 0.97. As the ratio of thesiloxane units is controlled as described above, suitable physicalproperties according to an application can be ensured. In oneembodiment, in the average empirical formula of Formula 5, all off and gmay not be 0. When all of f and g are not 0, f/g may be in the range of0.3 to 2.0, 0.3 to 1.5, or 0.5 to 1.5.

A polymerization product including the polyorganosiloxane (A) may be,for example, a ring-opening polymerization product of a mixtureincluding a cyclic polyorganosiloxane. When the polyorganosiloxane (A)has a partially-crosslinked structure, the mixture may further include,for example, a polyorganosiloxane having a cage or partial cagestructure, or including a T unit. As the cyclic polyorganosiloxanecompound, for example, a compound represented by Formula 6 may be used.

In Formula 6, R^(d) and R^(e) are each independently an epoxy group, ora monovalent hydrocarbon group, and o is 3 to 6.

The cyclic polyorganosiloxane may also include a compound of Formula 7and a compound of Formula 8.

In Formulas 7 and 8, R^(f) and R^(g) are each an epoxy group or an alkylgroup, R^(h) and R^(i) are each an epoxy group or an aryl group, p is anumber of 3 to 6, and q is a number of 3 to 6. In Formulas 7 and 8,R^(f) and R^(g) are each independently an alkyl group, and R^(h) andR^(i) may be each independently an aryl group.

In Formulas 6 to 8, specific kinds of R^(f) to R^(i), specific values ofo, p and q, and a ratio of components in the mixture, may be determinedby a desired structure of the polyorganosiloxane (A).

When the polyorganosiloxane (A) has a partially-crosslinked structure,the mixture may further include, for example, a compound having anaverage empirical formula of Formula 9, or a compound having an averageempirical formula of Formula 10.[R^(j)SiO_(3/2)]  [Formula 9][R^(k)R^(l) ₂SiO_(1/2)]_(p)[R^(m)SiO_(3/2)]_(q)  [Formula 10]

In Formulas 9 and 10, R^(j), R^(k) and R^(m) are each independently anepoxy group or a monovalent hydrocarbon group, R^(l) is an epoxy group,or an alkyl group having 1 to 4 carbon atoms, p is 1 to 3, and q is 1 to10.

In Formulas 9 to 10, specific kinds of R^(j) to R^(m), specific valuesof p and q, and a ratio of components in the mixture, may be determinedby a desired structure of the polyorganosiloxane (A).

When the cyclic polyorganosiloxane reacts with a polyorganosiloxanehaving a cage or partial cage structure, or including a T unit, apolyorganosiloxane having a desired partially-crosslinked structure maybe synthesized at a suitable molecular weight. In addition, according tothe method, by minimizing a functional group such as an alkoxy group ora hydroxyl group binding to a silicon atom in the polyorganosiloxane ora polymerization product including the same, a desired product havingexcellent physical properties can be prepared.

In one embodiment, the mixture may further include a compoundrepresented by Formula 11.(R^(n)R^(o) ₂Si)₂O  [Formula 11]

In Formula 11, R^(n) and R^(o) are each an epoxy group, or a monovalenthydrocarbon group.

In Formula 11, a specific kind of the monovalent hydrocarbon group or ablending ratio in the mixture may be determined by a desiredpolyorganosiloxane (A).

A reaction of each component in the mixture may be performed in thepresence of a suitable catalyst. Accordingly, the mixture may furtherinclude a catalyst.

As the catalyst that can be included in the mixture, for example, a basecatalyst may be used. A suitable base catalyst may be, but is notlimited to, a metal hydroxide such as KOH, NaOH or CsOH; a metalsilanolate including an alkali metal compound and a siloxane; or aquaternary ammonium compound such as tetramethylammonium hydroxide,tetraethyl ammonium hydroxide or tetrapropylammonium hydroxide.

A ratio of the catalyst in the mixture can be suitably selected inconsideration of desired reactivity, and for example, may be 0.01 to 30or 0.03 to 5 parts by weight relative to 100 parts by weight of a totalweight of the reaction products in the mixture. In the specification,unless particularly defined otherwise, units “parts by weight” refer toa weight ratio between components.

In one embodiment, the reaction of the mixture may be performed under asolvent-free condition in which a solvent is not used, or in thepresence of a suitable solvent. As a solvent, any kind of solvent inwhich the reaction product in the mixture, that is, a disiloxane orpolysiloxane, can be suitably mixed with a catalyst and does notinterfere with reactivity may be used. The solvent may be, but is notlimited to, an aliphatic hydrocarbon-based solvent such as n-pentane,i-pentane, n-hexane, i-hexane, 2,2,4-trimethyl pentane, cyclohexane ormethylcyclohexane; an aromatic solvent such as benzene, toluene, xylene,trimethyl benzene, ethyl benzene or methylethyl benzene; a ketone-basedsolvent such as methylethylketone, methylisobutylketone, diethylketone,methyl n-propyl ketone, methyl n-butyl ketone, cyclohexanone,methylcyclohexanone or acetylacetone; an ether-based solvent such astetrahydrofuran, 2-methyl tetrahydrofuran, ethyl ether, n-propyl ether,isopropyl ether, diglyme, dioxine, dimethyldioxine, ethyleneglycolmonomethyl ether, ethyleneglycol dimethyl ether, ethyleneglycol diethylether, propyleneglycol monomethyl ether or propyleneglycol dimethylether; an ester-based solvent such as diethyl carbonate, methyl acetate,ethyl acetate, ethyl lactate, ethyleneglycol monomethylether acetate,propyleneglycol monomethylether acetate or ethyleneglycol diacetate; oran amide-based solvent such as N-methylpyrrolidone, formamide, N-methylformamide, N-ethyl formamide, N,N-dimethyl acetamide orN,N-diethylacetamide.

The reaction of the mixture may be performed by adding the catalyst tothe reaction product at a reaction temperature of, for example, 0° C. to150° C. or 30° C. to 130° C. In addition, a reaction time may becontrolled within a range of, for example, 1 hour to 3 days.

The polyorganosiloxane (A) or a polymerization product including thesame may have a ratio of an area of a peak derived from an alkoxy groupbinding to a silicon atom with respect to an area of a peak derived froma functional group containing an aliphatic unsaturated bond binding tosilicon, for example, an alkenyl group such as a vinyl group, in aspectrum obtained by ¹H NMR, of 0.01 or less, 0.005 or less, or 0. Inthe above range, suitable viscosity can be exhibited, and other physicalproperties can be excellently maintained.

The polyorganosiloxane (A) or the polymerization product including thesame may have an acid value obtained by KOH titration of 0.02 or 0.01 orless, or 0. In the above range, suitable viscosity can be exhibited, andother physical properties can also be excellently maintained.

The polyorganosiloxane (A) or the polymerization product including thesame may have a viscosity at 25° C. of 500 cP or more, 1000 cP or more,2000 cP or more, or 5000 cP or more. In the above range, processabilityand hardness can be suitably maintained. The upper limit of theviscosity is not particularly limited, and the viscosity may be, forexample, 500000 cP or less, 400000 cP or less, 300000 cP or less, 200000cP or less, 100000 cP or less, 80000 cP or less, 70000 cP or less, or65000 cP or less.

The polyorganosiloxane (A) or the polymerization product including thesame may have a weight average molecular weight (Mw) of 500 to 50,000 or1,500 to 30,000. The term “weight average molecular weight” used hereinmay refer to a conversion value with respect to standard polystyrenemeasured by gel permeation chromatography (GPC), and unless particularlydefined otherwise, the term “molecular weight” used herein may refer toa weight average molecular weight. In the range of the molecular weightdescribed above, moldability, hardness and strength can be suitablymaintained.

The curable composition may further include a crosslinkablepolyorganosiloxane (hereinafter, referred to as “polyorganosiloxane(B)”. The term “crosslinkable polyorganosiloxane” may refer to apolyorganosiloxane essentially including a T or Q unit as a siloxaneunit, and having a ratio (D/(D+T+Q)) of a D unit with respect to D, Tand Q units of less than 0.65.

A crosslinkable polyorganosiloxane may have an average empirical formulaof Formula 12.(R¹¹ ₃SiO_(1/2))_(a)(R¹¹₂SiO_(2/2))_(b)(R¹¹SiO_(3/2))_(c)(SiO_(4/2))_(d)  [Formula 12]

In Formula 12, R¹¹ are each independently an epoxy group, or amonovalent hydrocarbon group, at least one of R¹¹ is an alkenyl group,at least one of R¹¹ is an aryl group, a is a positive number, b is 0 ora positive number, c is a positive number, d is 0 or a positive number,b/(b+c+d) is less than 0.65, 0.5 or less, or 0.3 or less, and c/(c+d) ismore than 0.8, 0.85 or more, or 0.9 or more.

In Formula 12, at least one or two of R¹¹ may be an alkenyl group. Inone embodiment, the alkenyl group may be present in such an amount thata molar ratio (Ak/Si) of the alkenyl group (Ak) with respect to allsilicon atoms (Si) included in the polyorganosiloxane (B) isapproximately 0.05 to 0.4 or 0.05 to 0.35. As the molar ratio (Ak/Si) iscontrolled to 0.05 or more, reactivity can be excellently maintained,and leakage of an unreacted component from a surface of the curedproduct can be prevented. In addition, as the molar ratio (Ak/Si) iscontrolled to 0.4 or less, or 0.35 or less, the hardness, crackresistance, and thermal and shock resistance of the cured product can beexcellently maintained.

In Formula 12, at least one of R¹¹ may be an aryl group. Accordingly,the refractive index and hardness of the cured product can beeffectively controlled. The aryl group may be present in such an amountthat a molar ratio (Ar/Si) of the aryl group (Ar) with respect to allsilicon atoms (Si) included in the polyorganosiloxane (B) isapproximately 0.5 to 1.5, or 0.5 to 1.2. As the molar ratio (Ar/Si) iscontrolled to 0.5 or more, the refractive index and hardness of thecured product can be maximized, and as the molar ratio (Ar/Si) iscontrolled to 1.5 or less, or 1.2 or less, the viscosity and thermal andshock resistance of the composition can be suitably maintained.

In the average empirical formula of Formula 12, a, b, c and d are molarratios of respective siloxane units. For example, when the sum (a+b+c+d)thereof is adjusted to be 1, a is 0.05 to 0.5, b is 0 to 0.3, c is 0.6to 0.95, and d is 0 to 0.2. To maximize strength, crack resistance andthermal and shock resistance of the cured product, (a+b)/(a+b+c+d) maybe controlled to 0.2 to 0.7, b/(b+c+d) may be controlled to less than0.65, 0.5 or less, or 0.3 or less, and c/(c+d) may be controlled to morethan 0.8, 0.85 or more, or 0.9 or more. Here, the lower limit ofb/(b+c+d) is not particularly limited, and for example, may be 0. Inaddition, here, the upper limit of c/(c+d) is not particularly limited,and for example, may be 1.0.

The polyorganosiloxane (B) may have a viscosity at 25° C. of 5000 cP ormore, or 1000000 cP or more, and therefore processability before curingand hardness after curing can be suitably maintained.

In addition, the polyorganosiloxane (B) may have, for example, amolecular weight of 800 to 20000, or 800 to 10000. As the molecularweight is controlled to 800 or more, moldability before curing andstrength after curing can be effectively maintained, and as themolecular weight is controlled to 20000 or less, or 10000 or less, theviscosity can be maintained at a suitable level.

A method of preparing the polyorganosiloxane (B) may be, for example, amethod of preparing a polysiloxane conventionally known in the art, or amethod similar to that of preparing the polyorganosiloxane (A).

The polyorganosiloxane (B) may be included such that, for example, aweight ratio (A/(A+B)) of the polyorganosiloxane (A) with respect to amixture of the polyorganosiloxane (A) and the polyorganosiloxane (B) isapproximately 10 to 50. In the above range, strength and thermal andshock resistance of the cured product can be excellently maintained, andsurface stickiness can also be prevented.

The curable composition may further include a silicon compound includinga hydrogen atom binding to a silicon atom (hereinafter, referred to as“silicon compound (C)”). The silicon compound (C) may have at least oneor two hydrogen atoms.

The silicon compound (C) may serve as a crosslinking agent to crosslinka composition by a reaction with a functional group containing analiphatic unsaturated bond of a polyorganosiloxane. For example,crosslinking and curing may be performed by addition-reacting a hydrogenatom of the silicon compound (C) and an alkenyl group of thepolyorganosiloxane (A) or (B).

As the silicon compound (C), any one of various kinds of siliconcompounds including a hydrogen atom binding to a silicon atom (Si—H) ina molecule may be used. The silicon compound (C) may be, for example, alinear, branched, cyclic, or crosslinkable organopolysiloxane. Thesilicon compound (C) may be a compound having 2 to 1000 silicon atoms,and preferably 3 to 300 silicon atoms.

The silicon compound (C) may be, for example, a compound of Formula 13,or a compound having an average empirical formula of Formula 14.R¹² ₃SiO(R¹² ₂SiO)_(n)SiR¹² ₃  [Formula 13](R¹³ ₃SiO_(1/2))_(a)(R¹³₂SiO_(2/2))_(b)(R¹³SiO_(3/2))_(c)(SiO₂)_(d)  [Formula 14]

In Formulas 13 and 14, R¹² are each independently hydrogen, or amonovalent hydrocarbon group, at least two of R¹² are hydrogen atoms, atleast one of R¹² is an aryl group, n is 1 to 100, R¹³ are eachindependently hydrogen or a monovalent hydrocarbon group, at least twoof R¹³ are hydrogen atoms, at least one of R¹³ is an aryl group, a is apositive number, b is 0 or a positive number, c is a positive number,and d is 0 or a positive number. For example, when the sum (a+b+c+d)thereof is adjusted to be 1, a is 0.1 to 0.8, b is 0 to 0.5, c is 0.1 to0.8, and d is 0 to 0.2.

The compound of Formula 13 is a linear siloxane compound having at leasttwo hydrogen atoms binding to a silicon atom. In Formula 13, n may be 1to 100, 1 to 50, 1 to 25, 1 to 10, or 1 to 5.

The compound represented as the average empirical formula of Formula 14may be a polysiloxane having a crosslinked or partially-crosslinkedstructure.

In one embodiment, a molar ratio (H/Si) of a hydrogen atom (H) bindingto a silicon atom with respect to all silicon atoms (Si) included in thesilicon compound (C) may be approximately 0.2 to 0.8 or 0.3 to 0.75. Asthe molar ratio is controlled to 0.2 or 0.3 or more, curability of thecomposition can be excellently maintained, and as the molar ratio iscontrolled to 0.8 or 0.75 or less, crack resistance and thermal andshock resistance can be excellently maintained.

The silicon compound (C) may include at least one aryl group, and thusat least one of R¹² in Formula 13 or at least one R¹³ in Formula 14 maybe an aryl group, for example, an aryl group having 6 to 21, 6 to 18, or6 to 12 carbon atoms, or a phenyl group. Accordingly, the refractiveindex and hardness of the cured product can be effectively controlled.The aryl group may be present in such an amount that a molar ratio(Ar/Si) of the aryl group (Ar) with respect to all silicon atoms (Si)included in the polyorganosiloxane (C) is approximately 0.5 to 1.5 or0.5 to 1.3. As the molar ratio (Ar/Si) is controlled to 0.5 or more, therefractive index and hardness of the cured product can be maximized, andas the molar ratio (Ar/Si) is controlled to 1.5 or 1.3 or less, theviscosity and crack resistance of the composition can be suitablymaintained.

The compound (C) may have a viscosity at 25° C. of 0.1 cP to 100000 cP,0.1 to 10000 cP, 0.1 cP to 1000 cP, or 0.1 cP to 300 cP. In the aboverange of viscosity, processability of the composition and hardness ofthe cured product can be excellently maintained.

In addition, the compound (C) may have, for example, a molecular weightof less than 2,000, less than 1,000 or less than 800. When the molecularweight is 1,000 or more, strength of the cured product may be degraded.The lower limit of the molecular weight of the compound (C) is notparticularly limited, and may be, for example, 250. In the compound (C),the molecular weight may be a weight average molecular weight, or aconventional molecular weight of the compound.

A method of preparing the compound (C) is not particularly limited, andmay employ a conventional method of preparing a polyorganosiloxane knownin the art, or a method similar to that of preparing thepolyorganosiloxane (A).

A content of the compound (C) may be selected within the range of amolar ratio (H/Ak) of a hydrogen atom (H) binding to a silicon atomincluded in the compound (C) with respect to all aliphatic unsaturatedbond-containing functional groups included in the curable composition,for example, all functional groups (Ak) containing an aliphaticunsaturated bond such as an alkenyl group included in thepolyorganosiloxane (A) and/or (B) of approximately 0.5 to 2.0 or 0.7 to1.5. Within the above range of the molar ratio (H/Ak), the compositioncan exhibit excellent processability and workability before curing,excellent crack resistance, hardness, thermal and shock resistance, andadhesiveness after curing, and cannot cause whitening or surfacestickiness even under harsh conditions.

The curable composition may further include a polyorganosiloxaneincluding functional groups having an aliphatic unsaturated bond, forexample, an alkenyl group and an epoxy group (hereinafter, referred toas “polyorganosiloxane (D)”).

The polyorganosiloxane (D) may serve as, for example, a tackifier toenhance adhesive strength.

In one embodiment, the polyorganosiloxane (D) may be represented as anaverage empirical formula of Formula 15.(R¹⁴ ₃SiO_(1/2))_(a)(R¹⁴₂SiO_(2/2))_(b)(R¹⁴SiO_(3/2))_(c)(SiO_(4/2))_(d)  [Formula 15]

In Formula 15, R¹⁴ are each independently an epoxy group, or amonovalent hydrocarbon group, at least one of R¹⁴ is an alkenyl group,at least one of R¹⁴ is an epoxy group, a, b, c and d are eachindependently 0 or a positive number, (c+d)/(a+b+c+d) may be 0.2 to 0.7,and c/(c+d) may be 0.8 or more. For example, when the sum (a+b+c+d) isadjusted to be 1, a may be 0 to 0.7, b may be 0 to 0.5, c may be 0 to0.8, and d may be 0 to 0.2.

In Formula 15, one or at least two of R¹⁴ may be an alkenyl group. Inone embodiment, the alkenyl group may be present in such an amount thata molar ratio (Ak/Si) of the alkenyl group (Ak) with respect to allsilicon atoms (Si) included in the polyorganosiloxane (D) is 0.05 to0.35, or 0.05 to 0.3. In such a molar ratio (Ak/Si), a cured productwhich exhibits excellent reactivity to another compound, forms acovalent bond with a silicon resin after curing, thereby havingexcellent adhesive strength, and has excellent physical properties suchas shock resistance, can be provided.

In Formula 15, at least one of R¹⁴ may also be an epoxy group.Accordingly, the strength and scratch resistance of the cured productcan be suitably maintained, and excellent adhesiveness can be achieved.The epoxy group may be present in such an amount that a molar ratio(Ep/Si) of the epoxy group (Ep) with respect to all silicon atoms (Si)included in the polyorganosiloxane (D) may be 0.1 or more, or 0.2 ormore. In such a molar ratio (Ep/Si), a crosslinked structure of thecured product can be suitably maintained, and heat resistance andadhesiveness can also be excellently maintained. The upper limit of themolar ratio (Ep/Si) is not particularly limited, and may be, forexample, 1.0.

In the average empirical formula of Formula 15, a, b, c and d are molarratios of respective siloxane units, and when the sum thereof isadjusted to be 1, a may be 0 to 0.7, b may be 0 to 0.5, c may be 0 to0.8, d may be 0 to 0.2. Here, c and d may not be simultaneously 0. Tomaximize strength, crack resistance and thermal and shock resistance ofthe cured product, (c+d)/(a+b+c+d) may be controlled to 0.3 to 0.7, andc/(c+d) may be controlled to 0.8 or more. Here, the upper limit ofc/(c+d) is not particularly limited, and for example, may be 1.0.

The polyorganosiloxane (D) may have a viscosity at 25° C. of 100 cP ormore, or 100000 cP or more, and therefore processability before curingand hardness after curing can be suitably maintained.

The polyorganosiloxane (D) may have, for example, a molecular weight of1000 cP or more, or 1500 or more. As the molecular weight is controlledto 1000 or more, or 1500 or more, a cured product having excellentprocessability and workability before curing, and excellent crackresistance, thermal and shock resistance and adhesiveness to a substrateafter curing can be provided. The upper limit of the molecular weight isnot particularly limited, and may be, for example, 20000.

A method of preparing the polyorganosiloxane (D) is not particularlylimited, and may employ, for example, a conventional method of preparinga polyorganosiloxane known in the art, or a method similar to that ofpreparing the polyorganosiloxane (A).

The polyorganosiloxane (D) may be included in an amount of, for example,0.2 to 10 parts by weight, or 0.5 to 5 parts by weight relative to 100parts by weight of a total weight of other compounds included in thecurable composition, for example, the polyorganosiloxane (A), thepolyorganosiloxane (B), and/or the silicon compound (C). In the aboverange, adhesiveness and transparency can be excellently maintained.

The curable composition may include a fiber-type filler, for example, afiber-type inorganic filler. The term “fiber-type filler” used hereinmay refer to a filler having a relatively large horizontal length(particle size, inner diameter, or outer diameter) with respect to avertical length (length of the filler) based on a single strand, forexample, a filler having an aspect ratio (vertical length/horizontallength) of 5 or more, 10 or more, 20 or more, 30 or more, 40 or more, 50or more, or 100 or more. In the fiber-type filler, the aspect ratio(vertical length/horizontal length) may be, for example, 2000 or less,1600 or less, 1500 or less, 1200 or less, 1000 or less, 700 or less, 500or less, or 400 or less.

The fiber-type filler may be a hollow fiber-type filler. The term“hollow fiber-type filler” may refer to a filler having a hole inside,for example, a pipe-shaped filler. When an aspect ratio of the hollowfiber-type filler is calculated, the horizontal length may be, forexample, an inner or outer diameter of the fiber.

The fiber-type filler, particularly, a hollow fiber-type filler has alower crystallinity, less interactivity between particles, and higherdispersity than other types of fillers, for example, a planar, sphericalor another shape of filler. Accordingly, such a filler may inhibit anincrease in viscosity of the composition, and may be less agglomerated.In addition, since the fiber-type filler has an anisotropic structure,it is preferable for enhancing mechanical characteristic and crackresistance, and has excellent thixotropy, thereby effectively inhibitingprecipitation of a fluorescent material with a small amount.

The particle size of a single strand of the fiber-type filler, or theinner or outer diameter of the single strand of the hollow fiber-typefiller is not particularly limited, but may be, for example,approximately 0.5 nm to 1,000 nm, 0.5 nm to 800 nm, 0.5 nm to 600 nm,0.5 nm to 500 nm, 0.5 nm to 300 nm, 0.5 nm to 200 nm, 1 nm to 150 nm, 1nm to 100 nm, 1 nm to 80 nm, 1 nm to 60 nm, or 1 nm to 50 nm.

The fiber-type filler may have a refractive index of, for example,approximately 1.45 or more. In addition, the fiber-type filler maysatisfy Equation 1.|X−Y|≦0.1  [Equation 1]

In Equation 1, X is a refractive index of the curable composition or acured product thereof excluding the filler, and Y is a refractive indexof the filler.

The term “refractive index” used herein may be, for example, arefractive index measured with respect to light having a wavelength of450 nm. In the above range, as transparency of the composition or thecured product is maintained to be applied to an element, a brightnessthereof can be enhanced. In Equation 1, |X−Y| may be, for example, 0.07or less, or 0.05 or less.

As the fiber-type filler, imogolite or halloysite may be used. Imogoliteis a hollow fiber-type compound derived from aluminum silicate andrepresented as Al₂SiO₃(OH)₄, and holloysite is also a hollow fiber-typecompound derived from aluminum silicate and represented asAl₂Si₂O₅(OH)₄.

The filler may be included in an amount of 0.5 to 70 parts by weight, 1to 50 parts by weight, 5 to 50 parts by weight, 10 to 50 parts byweight, or 10 to 40 parts by weight in the curable composition, forexample, relative to 100 parts by weight of the polyorganosiloxane (A).As the weight ratio of the fiber-type filler is controlled to 0.5 partsby weight or more, a mechanical characteristic, crack resistance andthermal resistance of the composition or cured product can be enhanced,thereby improving reliability of the element. In addition, as the weightratio is controlled to 70 parts by weight or less, processability can beexcellently maintained.

The curable composition may further include a hydrosilylation catalyst.The hydrosilylation catalyst may be used to stimulate a hydrosilylationreaction. As a hydrosilylation catalyst, any conventional componentknown in the art may be used. As such a catalyst, a platinum-,palladium- or rhodium-based catalyst may be used. In the specification,a platinum-based catalyst may be used in consideration of catalystefficiency, and may be, but is not limited to, chloroplatinic acid,platinum tetrachloride, an olefin complex of platinum, an alkenylsiloxane complex of platinum or a carbonyl complex of platinum.

A content of the hydrosilylation catalyst is not particularly limited aslong as the hydrosilylation catalyst is included at a catalytic amount,that is, an amount capable of serving as a catalyst. Conventionally, thehydrosilylation catalyst may be used at 0.1 ppm to 200 ppm, andpreferably 0.2 ppm to 100 ppm based on an atomic weight of platinum,palladium or rhodium.

The curable composition may further include a tackifier, alone or incombination with the polyorganosiloxane (D), in order to further enhanceadhesiveness to various substrates. The tackifier is a component capableof improving self-adhesiveness to the composition or cured product, andmay improve self-adhesiveness particularly to a metal and an organicresin.

The tackifier may be, but is not limited to, a silane having at leastone or two functional groups selected from the group consisting of analkenyl group such as a vinyl group, a (meth)acryloyloxy group, ahydrosilyl group (SiH group), an epoxy group, an alkoxy group, analkoxysilyl group, a carbonyl group and a phenyl group; or an organicsilicon compound such as a cyclic or linear siloxane having 2 to 30silicon atoms, or 4 to 20 silicon atoms. In the specification, one or atleast two of the tackifiers may be additionally mixed.

The tackifier may be included in the composition in a content of 0.1parts by weight to 20 parts by weight relative to 100 parts by weight ofa total weight of other compounds included in the curable composition,for example, the polyorganosiloxane (A), the polyorganosiloxane (B),and/or the silicon compound (C), but the content can be suitably changedin consideration of desired improvement in adhesiveness.

The curable composition may further include one or at least two ofadditives including a reaction inhibitor such as 2-methyl-3-butyne-2-ol,2-phenyl-3-1-butyne-2-ol, 3-methyl-3-penten-1-yne,3,5-dimethyl-3-hexen-1-yne,1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclotetrasiloxane orethynylcyclohexane; an inorganic filler such as silica, alumina,zirconia or titania; a carbon-functional silane having an epoxy groupand/or alkoxysilyl group, a partial hydrolysis-condensation productthereof or a siloxane compound; a thixotropic agent such as a haze-phasesilica that can be used in combination with polyether; a conductivityproviding agent such as metal powder of silver, copper or aluminum orvarious carbon materials; or a color adjusting agent such as a pigmentor dye, as needed.

The curable composition may further include a fluorescent material. Inthis case, a kind of a fluorescent material which can be used is notparticularly limited and, for example, a conventional kind of afluorescent material applied to an LED package may be used to realizewhite light.

Another aspect of the present application provides a semiconductorelement, for example, an optical semiconductor element. The exemplarysemiconductor element may be encapsulated by an encapsulant including acured product of the curable composition. Examples of a semiconductorelement encapsulated by an encapsulant include a diode, a transistor, athyristor, a photocoupler, a CCD, a solid-phase image pick-up diode, amonolithic IC, a hybrid IC, an LSI, a VLSI or a light-emitting diode(LED). In one embodiment, the semiconductor element may be anlight-emitting diode (LED).

The LED may be formed by stacking a semiconductor material on asubstrate. The semiconductor material may be, but is not limited to,GaAs, GaP, GaAlAs, GaAsP, AlGaInP, GaN, InN, MN, InGaAlN or SiC. Inaddition, as the substrate, monocrystalline sapphire, spinel, SiC, Si,ZnO or GaN may be used.

In addition, to prepare the LED, when necessary, a buffer layer may beformed between a substrate and a semiconductor material. As the bufferlayer, GaN or MN may be used. A method of stacking a semiconductormaterial on a substrate may be, but is not particularly limited to,MOCVD, HDVPE or liquid growth. In addition, a structure of the LED maybe, for example, a monojunction including an MIS junction, a PNjunction, and a PIN junction, a heterojunction, or a doubleheterojunction. In addition, the LED may be formed using a single ormultiple quantum well structure.

In one embodiment, an emission wavelength of the LED may be, forexample, 250 to 550 nm, 300 to 500 nm, or 330 to 470 nm. The emissionwavelength may refer to a main emission peak wavelength. As the emissionwavelength of the LED is set in the above range, a white LED having alonger life span, high energy efficiency and high color expression canbe obtained.

The LED may be encapsulated using the composition. In addition, theencapsulation of the LED may be performed only using the composition,and in some cases, another encapsulant may be used in combination withthe composition. When two kinds of encapsulant are used in combination,after the encapsulation using the composition, the encapsulated LED mayalso be encapsulated with another encapsulant. Alternatively, the LEDmay be first encapsulated with the other encapsulant and thenencapsulated again with the composition. As the other encapsulant, anepoxy resin, a silicon resin, an acryl resin, a urea resin, an imideresin, or glass may be used.

To encapsulate the LED with the composition, for example, a methodincluding injecting the composition into a mold beforehand, dipping alead frame to which the LED is fixed therein and curing the composition,or a method including injecting the composition into a mold into whichthe LED is inserted and curing the composition, may be used. As a methodof injecting the composition, injection by a dispenser, transfermolding, or injection molding may be used. In addition, as otherencapsulating methods, a method of dropping the composition on the LED,coating the composition by screen printing or using a mask, and curingthe composition, and a method of injecting the composition into a cup inwhich the LED is disposed on its bottom by a dispenser and curing thecomposition may be included.

In addition, the composition may be used as a diamond material fixingthe LED to a lead terminal or package, or a passivation layer or packagesubstrate on the LED as needed.

When it is necessary to cure the composition, the curing is notparticularly limited, and may be performed, for example, by maintainingthe composition at a temperature of 60 to 200° C. for 10 minutes to 5hours, or in 2 or more steps at suitable temperatures and for suitableamounts of time.

A shape of the encapsulant is not particularly limited, and for example,may be a bullet-shaped lens, planar shape, or thin film shape.

In addition, further enhancement of performance of the LED may bepromoted according to conventional methods known in the art. To enhanceperformance, for example, a method of disposing a reflective layer orlight collecting layer on a back surface of the LED, a method of forminga complementary coloring part on its bottom, a method of disposing alayer absorbing light having a shorter wavelength than the main emissionpeak on the LED, a method of encapsulating the LED and further moldingthe LED with a hard material, a method of inserting the LED into athrough hole to be fixed, or a method of contacting the LED with a leadmember by flip-chip contact to extract light from a direction of thesubstrate, may be used.

The LED may be effectively applied to, for example, backlights forliquid crystal displays (LCDs), lights, various kinds of sensors, lightsources of a printer and a copy machine, light sources for an automobilegauge, signal lights, pilot lights, display devices, light sources ofplanar LEDs, displays, decorations, or various kinds of lights.

Effect

A curable composition according to the present application exhibitsexcellent processability and workability. In addition, the curablecomposition exhibits excellent light extraction efficiency, hardness,thermal and shock resistance, moisture resistance, gas permeability andadhesiveness, after curing. In addition, the curable composition canprovide a cured product that exhibits long-lasting durability andreliability even under harsh conditions, and that does not causewhitening and surface stickiness.

ILLUSTRATIVE EMBODIMENTS

Hereinafter, a curable composition according to the present applicationwill be described in further detail with reference to Examples andComparative Examples, but the range of the curable composition is notlimited to the following Examples. Hereinafter, the abbreviation “Vi”refers to a vinyl group, the abbreviation “Ph” refers to a phenyl group,the abbreviation “Me” refers to a methyl group, and the abbreviation“Ep” refers to a 3-glycidoxypropyl group.

1. Measurement of Light Transmittance

Light transmittance of curable materials of Examples and ComparativeExamples was evaluated by the following method. A curable compositionwas injected between two glass substrates spaced approximately 1 mmapart from each other and cured at 150° C. for 1 hour, thereby preparinga planar sample having a thickness of 1 mm. Subsequently, lighttransmittance of the sample in a thickness direction with respect to awavelength of 450 nm was measured using a UV-VIS spectrometer at roomtemperature and then evaluated according to the following criteria.

<Criteria for Evaluating Light Transmittance>

◯: light transmittance of 85% or more

Δ: light transmittance of 75% or more, and less than 85%

X: light transmittance of less than 75%

2. Evaluation of Characteristics of Element

Characteristics of an element were evaluated using a 7030 LED packagemanufactured of polyphthalamide (PPA). Specifically, a curablecomposition was dispensed in a PPA cup, maintained at 70° C. for 30minutes, and then cured at 150° C. for 1 hour, thereby manufacturing asurface-mounted LED. Afterward, a test was performed according to thefollowing method.

(1) Thermal Shock Test

The LED was maintained at −40° C. for 30 minutes, and maintained againat 85° C. for 30 minutes, which was set as one cycle. This process wasrepeated 200 times, that is, for 200 cycles, and then the LED wasmaintained at room temperature. A peeling state was investigated toevaluate thermal and shock resistance. For evaluation, 20 LEDsmanufactured of the same curable composition were tested as describedabove, and a number of LEDs that exhibited peeling is shown in Table 1(number of peeled LEDs/total number of LEDs (20)).

(2) Long-Term Reliability Test

The manufactured LED was operated for 500 hours while 30 mA of currentwas supplied under conditions of 85° C. and relative humidity of 85%.Subsequently, a reduction rate of brightness after operation compared toinitial brightness before operation was measured and evaluated accordingto the following criteria.

<Evaluation Criteria>

A: brightness reduction rate of 5% or less with respect to initialbrightness

B: brightness reduction rate of more than 5% and also 7% or less withrespect to initial brightness

C: brightness reduction rate of more than 7% and also 9% or less withrespect to initial brightness

D: brightness reduction rate of more than 9% with respect to initialbrightness

Example 1

A curable composition capable of being cured by hydrosilylation wasprepared by mixing compounds represented by Formulas A to D (blendingamount: Formula A: 70 g, Formula B: 200 g, Formula C: 70 g, and FormulaD: 4 g). Here, the polyorganosiloxane of Formula A was prepared byreacting a mixture of octamethylcyclotetrasiloxane andoctaphenylcyclotetrasiloxane with divinyltetramethyldisiloxane in thepresence of a catalyst such as tetramethylammonium hydroxide (TMAH) atapproximately 115° C. for approximately 20 hours, and the compoundsother than the polyorganosiloxane of Formula A were prepared by knownsynthesis methods. Subsequently, a catalyst(platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane) was blended intothe composition in a content of Pt (0) of 10 ppm, and 20 g ofhollow-type imogolite having an average outer diameter of approximately2 mm and a length of approximately 400 nm was uniformly mixed, therebypreparing the curable composition.(ViMe₂SiO_(1/2))₂(Me₂SiO_(2/2))₁₆(Ph₂SiO_(2/2))₁₄  [Formula A](ViMe₂SiO_(1/2))₂(Ph₂SiO_(2/2))_(0.4)(PhSiO_(3/2))₆  [Formula B](HMe₂SiO_(1/2))₂(Ph₂SiO_(2/2))_(1.5)  [Formula C](ViMe₂SiO_(1/2))₂(EpSiO_(3/2))₃(MePhSiO_(2/2))₂₀  [Formula D]

Example 2

A curable composition capable of being cured by hydrosilylation wasprepared by mixing compounds represented by Formulas E, F, C and D(blending amount: Formula E: 70 g, Formula F: 200 g, Formula C: 70 g,and Formula D: 4 g). Here, the polyorganosiloxane of Formula E wasprepared by reacting a mixture of octamethylcyclotetrasiloxane andtetramethyltetraphenylcyclotetrasiloxane withdivinyltetramethyldisiloxane in the presence of a catalyst such astetramethylammonium hydroxide (TMAH), and the compounds other than thepolyorganosiloxane of Formula E were prepared by known synthesismethods. Subsequently, a catalyst(platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane) was blended intothe composition in a content of Pt(0) of 10 ppm, and approximately 20 gof hollow-type halloysite having an average inner diameter ofapproximately 50 mm and a length of approximately 8,000 nm was uniformlymixed, thereby preparing the curable composition.(ViMe₂SiO_(1/2))₂(PhMeSiO_(2/2))₂₆(Me₂SiO_(2/2))₄  [Formula E](ViMe₂SiO_(1/2))₂(MePhSiO_(2/2))_(0.4)(PhSiO_(3/2))₆  [Formula F](HMe₂SiO_(1/2))₂(Ph₂SiO_(2/2))_(1.5)  [Formula C](ViMe₂SiO_(1/2))₂(EpSiO_(3/2))₃(MePhSiO_(2/2))₂₀  [Formula D]

Example 3

A curable composition capable of being cured by hydrosilylation wasprepared by mixing compounds represented by Formulas G, H, C and D(blending amount: Formula G 70 g, Formula H: 200 g, Formula C: 70 g, andFormula D: 4 g). Here, the polyorganosiloxane of Formula G was preparedby reacting a mixture of octamethylcyclotetrasiloxane,octaphenylcyclotetrasiloxane, octaphenyl-polyhedral oligomericsilsesquioxane (octaphenyl-POSS) and divinyltetramethyldisiloxane with acatalyst such as tetramethylammonium hydroxide (TMAH) at a suitabletemperature, and the other compounds were prepared by known synthesismethods. Subsequently, a catalyst(platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane) was blended intothe composition in a content of Pt(0) of 10 ppm, and approximately 20 gof hollow-type halloysite having an average inner diameter ofapproximately 30 mm and a length of approximately 10,000 nm wasuniformly mixed, thereby preparing the curable composition.(ViMe₂SiO_(1/2))₂(Me₂SiO_(2/2))₁₀(Ph₂SiO_(2/2))₁₀(PhSiO_(3/2))₃  [FormulaG](ViMe₂SiO_(1/2))₂(Ph₂SiO_(2/2))_(0.4)(PhSiO_(3/2))₆  [Formula H](HMe₂SiO_(1/2))₂(Ph₂SiO_(2/2))_(1.5)  [Formula C](ViMe₂SiO_(1/2))₂(EpSiO_(3/2))₃(MePhSiO_(2/2))₂₀  [Formula D]

Example 4

A curable composition capable of being cured by hydrosilylation wasprepared by mixing compounds represented by Formulas I, J, C and D(blending amount: Formula I: 70 g, Formula J: 200 g, Formula C: 70 g,and Formula D: 4 g). Here, the polyorganosiloxane of Formula I wasprepared by reacting a mixture of octamethylcyclotetrasiloxane andoctaphenylcyclotetrasiloxane with divinyltetramethyldisiloxane in thepresence of a catalyst such as tetramethylammonium hydroxide (TMAH), andthe other compounds were prepared by known synthesis methods.Subsequently, a catalyst(platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane) was blended intothe composition in a content of Pt(0) of 10 ppm, and approximately 20 gof hollow-type halloysite having an average inner diameter ofapproximately 40 mm and a length of approximately 5,000 nm was uniformlymixed, thereby preparing the curable composition.(ViMe₂SiO_(1/2))₂(Me₂SiO_(2/2))₁₄(Ph₂SiO_(2/2))₁₆  [Formula I](ViMe₂SiO_(1/2))₂(Ph₂SiO_(2/2))_(0.4)(PhSiO_(3/2))₆  [Formula J](HMe₂SiO_(1/2))₂(Ph₂SiO_(2/2))₁₅  [Formula C](ViMe₂SiO_(1/2))₂(EpSiO_(3/2))₃(MePhSiO_(2/2))₂₀  [Formula D]

Comparative Example 1

A curable composition was prepared by the same method as described inExample 1, except that imogolite was nut blended.

Comparative Example 2

A curable composition was prepared by the same method as described inExample 1, except that imogolite was not blended and silica particleshaving an average particle size of approximately 20 nm were used.

Comparative Example 3

A curable composition was prepared by the same method as described inExample 1, except that imogolite was not blended and glass flakes(REP-015, Nippon Itarahas) were used.

Comparative Example 4

A curable composition was prepared by the same method as described inExample 1, except that imogolite was not blended and montmorilloniteclay was used.

Comparative Example 5

A curable composition was prepared by the same method as described inExample 1, except that imogolite was not blended and alumina fiberhaving a diameter of approximately 2 nm and a length of approximately400 nm was used as a fiber-type filler, not a hollow-type filler.

Physical properties measured with respect to the Examples andComparative Examples were measured and summarized in Table 1.

TABLE 1 Light Thermal and Long-term transmittance shock resistancereliability Example 1 O 0/20 A Example 2 O 0/20 B Example 3 O 0/20 AExample 4 O 0/20 A Comparative O 16/20  D Example 1 Comparative C — —Example 2 Comparative C 4/20 C Example 3 Comparative C 6/20 C Example 4Comparative C 4/20 C Example 5 In Comparative Example 2, since theviscosity of the composition was very high, it was impossible tomanufacture an LED, and thus physical properties, other than lighttransmittance, were impossible to measure.

What is claimed is:
 1. A curable composition, comprising: apolymerization product comprising a polyorganosiloxane comprising anaryl group and a functional group having an aliphatic unsaturated bond;and a filler in the shape of a hollow fiber, wherein the filler in theshape of the hollow fiber has an aspect ratio of 50 or more.
 2. Thecurable composition according to claim 1, wherein the polyorganosiloxanecomprises a unit of Formula 2 and a unit of Formula 3:(R¹R²SiO_(2/2))  [Formula 2](R³ ₂SiO_(2/2))  [Formula 3] wherein R¹ and R² are each independently anepoxy group or a monovalent hydrocarbon group, and R³ is an aryl group.3. The curable composition according to claim 2, wherein a ratio (M₂/M₃)of moles (M₂) of the unit of Formula 2 with respect to moles (M₃) of theunit of Formula 3 is from 0.3 to 2.0.
 4. The curable compositionaccording to claim 1, wherein the polyorganosiloxane has an averageempirical formula of Formula 4:(R⁴ ₃SiO_(1/2))_(a)(R⁴₂SiO_(2/2))_(b)(R⁴SiO_(3/2))_(c)(SiO_(4/2))_(d)  [Formula 4] where R⁴'sare each independently an epoxy group or a monovalent hydrocarbon group,with the proviso that at least one of R⁴'s is an alkenyl group and atleast one of R⁴'s is an aryl group; and a and b are each a positivenumber, c and d are each 0 or a positive number, and b/(b+c+d) is 0.7to
 1. 5. The curable composition according to claim 1, whereinpolyorganosiloxane has an average empirical formula of Formula 5:(R⁵R⁶ ₂SiO_(1/2))_(e)(R⁷R⁸SiO_(2/2))_(f)(R⁹₂SiO_(2/2))_(g)(R¹⁰SiO_(3/2))_(h)  [Formula 5] wherein R⁵ is amonovalent hydrocarbon group, R⁶ is an alkyl group having 1 to 4 carbonatoms, R⁷ and R⁸ are each independently an alkyl group, an alkenylgroup, or an aryl group, R⁹ is an aryl group, e is a positive number, f,g, and h are each 0 or a positive number, and (f+g)/(f+g+h) is 0.7 to 1.6. The curable composition according to claim 1, wherein thepolymerization product is a polymerization product of a mixturecomprising a compound of Formula 6:

wherein R^(d) and R^(e) are each independently an epoxy group or amonovalent hydrocarbon group, and o is 3 to
 6. 7. The curablecomposition according to claim 1, wherein the polymerization product isa polymerization product of a mixture comprising a compound of Formula 7and a compound of Formula 8,

wherein R^(f) and R^(g) are each an epoxy group or an alkyl group, R^(h)and R^(i) are each an epoxy group of an aryl group, p is a number of 3to 6, and q is a number of 3 to
 6. 8. The curable composition accordingto claim 6 or 7, wherein the mixture further comprises apolyorganosiloxane having an average empirical formula of Formula 9 or10:[R^(j)SiO_(3/2)]  [Formula 9][R^(k)R^(l) ₂SiO_(1/2)]_(p)[R^(m)SiO_(3/2)]_(q)  [Formula 10] whereinR^(j), R^(k) and R^(m) are each independently an epoxy group or amonovalent hydrocarbon group, R^(l) is an alkyl group having 1 to 4carbon atoms, p is 1 to 3, and q is 1 to
 10. 9. The curable compositionaccording to claim 1, wherein the filler in the shape of the hollowfiber has an inner or outer diameter of a single strand of 0.5 nm to1,000 nm.
 10. The curable composition according to claim 1, wherein thefiller in the shape of the hollow fiber satisfies Equation 1:|X−Y|≦0.1  [Equation 1] wherein X is a refractive index of the curablecomposition or a cured product thereof, which does not comprise thefiller in the shape of the hollow fiber, and Y is a refractive index ofthe filler in the shape of the hollow fiber.
 11. The curable compositionaccording to claim 10, wherein the filler in the shape of the hollowfiber has a refractive index of 1.45 or more.
 12. The curablecomposition according to claim 1, wherein the filler in the shape of thehollow fiber is an imogolite or a halloysite.
 13. The curablecomposition according to claim 1, wherein the filler in the shape of thehollow fiber is comprised in an amount of 0.5 parts by weight to 70parts by weight relative to 100 parts by weight of thepolyorganosiloxane.
 14. The curable composition according to claim 1,further comprising: a polyorganosiloxane having an average empiricalformula of Formula 12:(R¹¹ ₃SiO_(1/2))_(a)(R¹¹₂SiO_(2/2))_(b)(R¹¹SiO_(3/2))_(c)(SiO_(4/2))_(d)  [Formula 12] whereinR¹¹'s are each independently an epoxy group, or a monovalent hydrocarbongroup, with the proviso that at least one of R¹¹'s is an alkenyl groupand at least one of R¹¹'s is an aryl group; and a is a positive number,b is 0 or a positive number, c is a positive number, d is 0 or apositive number, b/(b+c+d) is less than 0.65, and c/(c+d) is 0.8 ormore.
 15. The curable composition according to claim 1, furthercomprising: a compound of Formula 13 or a compound having an averageempirical formula of Formula 14:R¹² ₃SiO(R¹² ₂SiO)_(n)SiR¹² ₃  [Formula 13](R¹³ ₃SiO_(1/2))_(a)(R¹³ ₂SiO_(2/2))_(b)R¹³SiO_(3/2))_(c)(SiO₂)_(d)wherein R¹²'s are each independently hydrogen, or a monovalenthydrocarbon group, with the proviso that at least two of R¹²'s arehydrogen atoms and at least one of R¹²'s is an aryl group; and n is 1 to100; R¹³'s are each independently hydrogen or a monovalent hydrocarbongroup, with the proviso that at least two of R¹³'s are hydrogen atomsand at least one of R¹³'s is an aryl group; and a is a positive number,b is 0 or a positive number, c is a positive number, and d is 0 or apositive number.
 16. An optical semiconductor encapsulated by the curedcurable composition of claim
 1. 17. A liquid crystal display comprisingthe optical semiconductor of claim 16 in a backlight unit.
 18. Alighting apparatus comprising the optical semiconductor of claim 16.